Photocatalytic Cellulose Reforming for H2 and Formate Production by Using Graphene Oxide-Dot Catalysts

The mechanism of photocatalytic biomass reforming for H2 production is far from fully understood. This study uses functionalized graphene dots with Pt-cocatalyst to reform cellulose in an alkaline solution under 1 sun illumination. Reforming of cellulose is initiated with the peeling of its constituent d-glucose units, which subsequently transform into deprotonated isosaccharinic acid (C6). Further degradation of C6 into molecules C5-C1 proceeds through successive alternation of C-eliminating hydrolysis and photocatalytic oxidation of C6 derivatives. The C6-C1 species are quantitatively identified using chromatography and mass spectroscopy. The end C-containing product is predominantly HCOO– rather than HCO3– (or CO2). The photocatalytic oxidation is accompanied by the photocatalytic reduction of water to produce H2. This reforming steadily produced H2 for 6 days with a negligible rate decay, accomplishing 35% of the theoretical ultimate value for the reforming of cellulose. This study elucidates the detailed mechanism in the photocatalytic reforming of cellulose.